Undo hints to speed up segment extension and tuning of undo retention

摘要

Methods and systems for using undo hints to speed up segment extension are disclosed. While a process is searching other segments to find available space, the process collects undo hints that describe when space in a segment might become available. These undo hints are placed in a table of undo hints. When a process is not able to find available space, it may consult the table of undo hints to determine how much to decrease the undo retention. After the undo retention is decreased, the process may again consult the table of undo hints to find a segment that likely contains available space now that the undo retention time has been reduced.